What is IBU and how does bitterness affect beer?

When we look at a bar's tap list, where the names and styles of the beers available that night are displayed, we can usually see two values right next to them: ABV and IBU. The first is easier to explain: ABV is the percentage of alcohol in a given beer. IBU, however, as we know, is not measured in percentages. So in this article we will take a closer look at what IBU is:

• How this unit of measurement works;
• What to expect from beers with different IBUs;
• How bitterness affects the drink.

What does IBU mean in beer?

A beer's IBU can range from 0 to 120. The higher the number, the more bitter the drink. It is measured at the end of production through chemical analysis, by determining how many milligrams of iso-alpha acids are dissolved in one liter of beer. In other words, 1 IBU = 1 mg of iso-alpha acids per liter. But what does that mean?

This chemical compound is the main source of a beer's bitterness. Iso-alpha acids are added to the beer by boiling the hops, a plant used to add different flavors and aromas. However, factors other than the amount of hops added are taken into account when defining a beer's IBU and altering its bitterness.

• Hops have different alpha acid levels, which can vary depending on the plant species, how it is grown or the region where it grows, for example.
• The gravity of the wort (the pre-fermentation beer) to which the hops were added is also taken into account.
• So are the boiling time required and the final volume of the liquid after this process.
• Other factors that can influence bitterness (and that have nothing to do with adding hops) are alcohol content, malt roast and additional ingredients or adjuncts.

The IBU scale

IBU, then, is not the only factor that determines the flavor of each beer. Often, bitterness can be masked by the addition of other rich ingredients. For that reason, the scale below will not necessarily apply to every style, but it is an important guide for new tasters.

What to expect from each IBU range

• 10 to 15 IBU: beers with a mild bitterness.
• 25 to 35 IBU: beers with a more pronounced hop flavor.
• 40 to 55 IBU: heavily hopped beers, common among IPAs.
• Above 60 IBU: extremely hoppy beers with obvious bitterness.

What to expect from some styles

• American Lager: between 8 and 25 IBU
• Red Ale: between 15 and 30 IBU
• Draft Pilsner or Pilsen: between 25 and 45 IBU
• Porter: between 18 and 50 IBU
• Bitter: between 24 and 50 IBU
• Stout: between 30 and 90 IBU
• India Pale Ale (IPA): wide variation, which can range from 40 to 120 IBU
• Brazilian mass-market beers: range from 8 to 15 IBU

The more bitter, the better?

With this content, you may have noticed that high bitterness is not a synonym for quality in a beer. The production process, the choice of ingredients and their proportions, as a whole, are what make a beer pleasant to the palate of a share of consumers. After all, there should be products for every taste, and no one should feel obliged to like something.

Malt and hops (and their amounts) dictate a beer's main flavors and aromas. Malt is the base that releases the sugars, while hops bring the bitterness. The art of brewing lies precisely in finding the best blend of these two elements. The fun is in tasting and discovering which style is best for you.

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